Method of bluing steel or iron sheets.



UNITED STAllIZ PATENT OFFICE.

JOHN E. CARNAHAN, OF CANTON, OHIO.

METHOD OF BLUING STEEL OR IRON SHEETS.

No Drawing.

T (117 whom it may concern Be it known that 1 JOHN E. CARNAHAN, a citizen of the United States, residing at Canton, in the county of Stark and State of Ohio. have invented a certain new and useful Method of Bluing Steel or Iron Sheets, of which the following is a. specification.

The invention relates to the oxidation of steel or iron sheets for the purpose of giting them a deep or dark blue finish. Ordinary oxidation by steam, air or other oxidizing agent gives them a comparatively light blue finish. which for many purposes is not as desirable or acceptable for commercial purposes as a darker blue finish.

The object of the present invention is attained by oxidizing the surface of the sheets in an aunealiing box as by the usual steam process, and at the same time subjecting the sheets to the action of sulfur vapor or fumes, which results in giving them a deeper and darker blue than can be produced by the steam or other oxidizing agent alone.

The improved process ma}: be performed by heating: the sheets in an annealing box to an annealing heat. and then cooling the sheets while incloscd in the box. to a dark red color. at \'-.'hich time steam or other oxidizing agent is introduced into the box in the usual manner for oxidhcing the sheets. and at the same time a small quantity of sulfur is introduced into the annealing box. as by placing; it in a small pan and insertin; the same under the rim of the annealin; box. by raising the box slightl: from its bed plate. The sulfur thus introduced into the annealing box may be in powdered, granular, or other convenient form. and may be from several ounces to a pound in weight. according to the size of the box. the surface area of the. sheets therein. and the particular depth or darkness of the blue to be produced on the sheets.

Specification of Letters Patent.

Patented June 1, 1915.

Application filed January 2, 1914. Serial No. 809,834.

Upon the introduction of the sulfur into the box, the heat therein very promptly converts the sulfur into a vapor, and the fumes rising therefrom permeate the pack of sheets and produce in the surface thereof the desired deep or dark blue color.

It will be understood that the sulfur can be introduced into the box and Will be properly vaporized, at any time While the heat therein is from 1500 F. down to about 700 l., within which range the best results have been obtained; and it will be furthermore understood, that it is not essential to introduce at one time, all the sulfur which may be ultimately required, but the same is preferably introduced at intervals during the cooling of the sheets, and is effective as long as the heat therein properly aporizes the I sulfur.

of hitting heated steel or consists in oxidizing the sheets by steam or other uXlkllilllfJ-tlfltllt. 80 I and at the same time subjecting: the sheets to the action of sulfur fumes at a temperature exceeding: 700 F.

JOHN E. (XXRXAHAN.

lVi tnesses:

EARL C. CARLsox, Lot'rsc M. Comm. 

